Synchronization support, Scheduler algos, and memory management of the OS. Write a code to connect Hardware interrupt to ISR? In case of high end processors the interrupt table will decide the interrupt vector address and whenever intterrupt pin goes low, the table is searched for type and source of interrupt.
What is task spawn in vxworks? Task Spawn is used to create a thread in VXworks. Once the thread is created than only we can make all the suspended,delete,resume operations. What version of wince supports dual core processor? When would you choose bottom up methodology? In Bottom Up Methodology, we build the bottom-most layer first and then ascend onto the actual application i.
Bottom Up methodology is followed when we are definite about the number, type and functionality of the Bottom most functions Assisting Functions to be defined. Once all these functions are defined, we build the bigger system above it. When would you choose top down methodology? Top down methodology is one where overall picture of the system is defined first. Then we go into the details of the sub-systems in the next level and so on. So to brief this, first the complex system is seen as a whole and then this is broken down to smaller simpler pieces.
Top down approach is preferred when understanding of the complete system is done. Sufficient knowledge of the system is required. Download Interview PDF. This is the technique used for memory protection.
Any accesses outside premitted area would result in segmentation fault. Same as paging. Write a code to check whether a stack grows upwards or downwards? For process synchronization, it is a mechanism to invoke the sleeping process to become ready for execution.
Its mechanism where a process can wait for resources to be available. The producer process creates resources and signals the semaphore saying resource is available. Consumer process waiting on the semaphore gets the signal that resource is available. Write a small piece of code protecting a shared memory variable with a semaphore?
Binary semaphore and counting semaphore. Binary semaphore is same as mutex. Binary semaphore tries to protect only one resource. Counting semaphore is used in case of multiple resource. For ex: we have 4 printers then the counting semaphore value will be init to 4.
When it reaches 0, the task waiting on the semaphore is suspended. What is present in. Until it is written to, it remains zeroed. What are the different segments of a program code, data,stack,heap etc memory Segments:.
Code segment : This phrase used to refer to a portion of memory or of an object file that contains executable computer instructions. It has a fixed size, since all of the data in this section is set by the programmer before the program is loaded. These are initialized to 0 and later assigned values during runtime. It is the responsibility of the programmer to deallocate it after its use.
Or alternatively it will be garbage collected by the OS. What is priority inversion? In a scenario where a low priority task holds a shared resource example semaphore that is required by a high priority task. This causes the execution of the high priority task to be blocked until the low priority task has released the resource. Locality of reference:It deals with a process accessing a resource multiple times.
Thread pool is a collection of managed threads usually organized in a queue, which execute the tasks in the task queue. Creating a new thread object every time you need something to be executed asynchronously is expensive. In a thread pool you would just add the tasks you wish to be executed asynchronously to the task queue and the thread pool takes care of assigning an available thread, if any, for the corresponding task.
As soon as the task is completed, the the now available thread requests another task assuming there is any left. In computer storage, fragmentation is a phenomenon in which storage space is used inefficiently, reducing storage capacity and in most cases performance.
The term is also used to. The biggest difference is determinacy. An RTOS will have a deterministic scheduler. For any given set of tasks your process will always execute every number of microseconds or milliseconds exactly, and the same number from schedule to schedule.
Modern RTOSs simply make sure that a no interrupt is ever lost, and b no interrupt can be blocked by a lower priority process.
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